Conventional amplifiers of this class comprise two symmetrical main transistors of one and the same conductivity type with emitters connected in parallel to an ungrounded terminal of a d-c supply via a common constant-current generator. In a prior system the collector of one of these main transistors is connected to a ground supply terminal through the forward resistance of a diode while the collector of the other main transistor is grounded via an ancillary, complementary transistor having is base/emitter circuit connected across that diode. When the base of the first main transistor receives an input signal, the base of the second main transistor being grounded, an unblanced output signal appears on the interconnected collectors of the second main transistor and of the ancillary transistor in series therewith. In order to compensate for the voltage drop across the diode and the substantially identical voltage drop across the base/emitter junction of the ancillary transistor, the input signal and the zero potential of the grounded supply terminal may be fed to the bases of the two main transistors not directly but through the base/emitter paths of two supplemental transistors connected therewith in a Darlington configuration. The presence of these supplemental input transistors, however, adversely affects the noise factor and the offset voltage of the differential amplifier.